Thermostat



Aug. 15, 1933. A, OSGQQD 1,922,451

THERMQSTAT Filed Sept. 25, 1931 y I M YNZ/E/VTUR flTTU A/Ex Patented Aug. 15, 1933 UNITED STATES PATENT OFFICE,

one-tenth to Greg.

Laurence Selling, Portland,

Application September 25, 1931 Serial No. 565,115

2 Claims. (01. 200-439) This invention relates generally to thermostats, and particularly to the type employing bimetallic thermostatic elements.

The main object of this invention is to pro- 5 vide anexceedingly simple and efficient form of thermostat which will have a rapid make and break action capable of eliminating objectionable arcing and rendering possible the use of this thermostat in ordinary lighting circuits without the use of relays or other protecting devices.

These, and other .objects, will become more apparent from the specification following as illustrated in the accompanying drawing, in which:

Fig. 1 is a plan of the thermostat with the case broken away in section.

Fig. 2 is a vertical section taken along the line 22 in Fig. 1 showing the parts in a circuitclosing position.

Fig. 3 is a side elevation a circuit-opening position.

showing the parts in Fig. 4 is a section taken along the line 4-4v in Fig. 1.

Similar numbers of reference refer to similarat an intermeflate point a'soft iron armature 16. Near the end 17 is positioned a contact point 18 adapted to engage the post. 19 when the end 17 is moved sufficiently toward the base 10.. The

binding post 20 is connected to the post 19 and the binding post'21 is connected to the element 14 through the insert 13. In the base 10 is placed-a threaded bushing 22 in which is a set screw 23 whose point bears against the rivet 24 which connects the bimetallic element 14 to the spring 11.-

With the exception of the armature 16 and the spring 11 the mechanism thus far described is quite similar to those now in common use.

Referring particularly to my invention same will be seen to consist in the inclusion of a horseshoe magnet 25 whose poles 26 are placed between the armature 16 and the base 10, against which post the magnet 25 is held by the screws 27, orin any other. convenient manner. 55. It must be understood that while a magnet of the horseshoe type is referred to that any other form of permanent or electro magnet may be employed Without departing from the spirit of this invention.

The operation of the device is as follows: The thermostat is placed in a control circuit by merely attaching the ends of the wires 28 and 29 to the bindingposts 20 and 21 respectively, and the instrument is-positioned, of course, near the point at which the temperature is to be controlled. It can readily be seen that a drop in temperature which will cause the element '14 to move toward the magnet 25 and eventually close the circuit through the point 18 and the post 19, will also cause the armature 16 to approach the poles 26 of the magnet 25.

While the movement of the end 17 of the element 14, occasioned by changes in temperature, is somewhat slow it can be seen that the armature 16 enters the field of the magnet 25 the abrupt. -LikeWise when the temperature rises and causes the element 14 to bend away from the post 19, the first portion of this tendency is to overcome by the holding action of the armature 16, storing up an initial tension in the spring of the element 14 which, when it exceeds the pull of the magnet, causes an extremely rapid separation of its contact points 18 and post 19, in either'case eliminating entirely a tendency. to are at ordinary lightingvoltages, thereby eliminating the so-called stuttering action common in thermostats relying entirely upon the heat changes: for the making and breaking of a circuit. v

It is obvious that the tension of the spring 11 and the spacing of the points 18 and post 19 may be regulated by means of the screw 23, or the spacing of the points 18 and the post 19 may be varied by inserting or removing oneor more washers 30 under the post 19, or between the armature 16 and the portion 15 of the bimetallic element 14.

It will be seen that the function of the magnet is to produce a rapid closing movement by a pull on the armature 16 just-before the closing action has been completed by the bimetallic element 14, and to retard the opening action after the time when it would have normally opened under the action of the'bimetallic element 14. In other words, the circuit is closed under the action of the magnet and opened under the action of the spring, and the biof i said spring, a contact post mounted on said base in the bath of movement of said bi-metallic element, an armature secured to said bi-metallic element between said post and spring, a horse shoe magnet secured against said base and having its poles in the path of said armature, and a screw for adjusting the tension of said spring.

2. The substance of claim 1, and means for adjusting the gap between the end of said bimetallic element and said contact post.

AUSTIN H. OSGOOD. 

